Part 3 — Digestive System & Associated Organs (Questions 51–75)
Part 3 — Digestive System & Associated Organs (Questions 51–75)
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The upper opening of the digestive tract in frog is called:
A. Cloaca
B. Mouth (buccal cavity)
C. Vent
D. Spiracle
Answer: B — Mouth (buccal cavity).
Explanations:
A: Incorrect — cloaca is the posterior common opening.
B: Correct — digestion begins in mouth/buccal cavity.
C: Incorrect — vent = cloacal opening.
D: Incorrect — spiracle is in some fishes. -
Frogs have vomerine teeth and maxillary teeth located in the:
A. Lower jaw only
B. Upper jaw/palate region aiding in holding prey
C. Oesophagus
D. Internal nostrils
Answer: B — Upper jaw/palate region aiding in holding prey.
Explanations:
A: Incorrect — lower jaw often toothless.
B: Correct — vomerine teeth on palate and maxillary teeth on upper jaw help grip prey.
C: Incorrect — oesophagus lacks such teeth.
D: Incorrect — not in nostrils. -
The frog’s tongue is attached at:
A. The front (anterior) of the lower jaw
B. The posterior region of buccal cavity (attached to the front of the lower jaw)
C. The roof of the mouth
D. The cloacal opening
Answer: B — The posterior region of buccal cavity (attached to the front of the lower jaw).
Explanations:
A: Incorrect — tongue is attached at anterior part of lower jaw but better expressed as on anterior floor of mouth with ability to flip out.
B: Correct — tongue is attached anteriorly and is highly protrusible to capture prey.
C: Incorrect — not fixed to roof.
D: Incorrect — cloaca unrelated. -
The specialised feeding mechanism where frog’s tongue flips out to capture prey is called:
A. Filter feeding
B. Projectile or protrusible tongue mechanism
C. Mastication
D. Suck feeding through gills
Answer: B — Projectile or protrusible tongue mechanism.
Explanations:
A: Incorrect — not filter feeding.
B: Correct — frog uses sticky, protrusible tongue to grab prey rapidly.
C: Incorrect — frogs swallow whole, not chew extensively.
D: Incorrect — gills not used in adults. -
Where does the chemical digestion of proteins primarily begin in frog?
A. Buccal cavity with salivary amylase
B. Stomach with pepsin-like enzymes and acidic environment
C. Mouth with lipase activity
D. Cloaca with digestive enzymes
Answer: B — Stomach with pepsin-like enzymes and acidic environment.
Explanations:
A: Incorrect — amphibian saliva not major in protein digestion; salivary amylase is a mammalian enzyme.
B: Correct — stomach secretes acidic juices and proteases initiating protein digestion.
C: Incorrect — lipase acts on fats, not primary for protein; lipase not major in mouth.
D: Incorrect — cloaca is exit chamber, not primary digestion. -
The junction between stomach and small intestine in frog is called the:
A. Pylorus
B. Cardia
C. Ileocaecal valve
D. Glottis
Answer: A — Pylorus.
Explanations:
A: Correct — pylorus (pyloric sphincter) regulates passage of food from stomach to small intestine (duodenum).
B: Incorrect — cardia is junction of oesophagus and stomach.
C: Incorrect — ileocaecal valve is between ileum and large intestine.
D: Incorrect — glottis leads to respiratory tract. -
In frog, bile is stored in:
A. Pancreas
B. Gall bladder (within hepatic system)
C. Stomach
D. Cloaca
Answer: B — Gall bladder (within hepatic system).
Explanations:
A: Incorrect — pancreas secretes pancreatic juice, not bile.
B: Correct — gall bladder stores bile produced by liver.
C: Incorrect — stomach stores food, not bile.
D: Incorrect — cloaca is exit chamber. -
The pancreas in frog contributes to digestion by secreting:
A. Only bile
B. Pancreatic enzymes like amylase, proteases and lipases into intestine
C. Saliva for chewing
D. Mucus to the skin only
Answer: B — Pancreatic enzymes like amylase, proteases and lipases into intestine.
Explanations:
A: Incorrect — bile is produced by liver.
B: Correct — pancreas secretes digestive enzymes into the duodenum for carbohydrate, lipid and protein digestion.
C: Incorrect — saliva produced by salivary glands, not pancreas.
D: Incorrect — pancreas does not secrete mucus to skin. -
The alimentary canal in frog includes which sequence (mouth to cloaca)?
A. Mouth → pharynx → oesophagus → stomach → small intestine → large intestine → cloaca
B. Mouth → crop → gizzard → intestine → cloaca
C. Mouth → stomach → gills → intestine → cloaca
D. Mouth → trachea → stomach → cloaca
Answer: A — Mouth → pharynx → oesophagus → stomach → small intestine → large intestine → cloaca.
Explanations:
A: Correct — this is standard vertebrate digestive sequence in frogs.
B: Incorrect — crop and gizzard are avian specializations.
C: Incorrect — gills not part of adult digestive tract.
D: Incorrect — trachea is respiratory; not digestive. -
The longest part of frog’s digestive tract where nutrient absorption mainly occurs is:
A. Stomach
B. Small intestine (duodenum & ileum)
C. Cloaca
D. Oesophagus
Answer: B — Small intestine (duodenum & ileum).
Explanations:
A: Incorrect — stomach mainly digestion, less absorption.
B: Correct — small intestine is main site for enzymatic digestion and absorption.
C: Incorrect — cloaca is common outlet, not absorption site.
D: Incorrect — oesophagus mainly transport. -
The liver in frog performs all the following EXCEPT:
A. Production of bile for fat emulsification
B. Detoxification and storage of glycogen
C. Secretion of digestive enzymes into stomach directly
D. Metabolic functions related to protein and carbohydrate metabolism
Answer: C — Secretion of digestive enzymes into stomach directly.
Explanations:
A: Incorrect statement — liver does produce bile (so not exception).
B: Incorrect statement — liver does detoxify and store glycogen (so not exception).
C: Correct — liver produces bile but not digestive enzymes and not secreted directly into the stomach.
D: Incorrect statement — liver is central metabolic organ. -
The caecum in frog’s gut is:
A. A sac-like outgrowth at the junction of small and large intestine that may assist in digestion/fermentation
B. Part of respiratory tract
C. The muscular stomach region for grinding
D. A kidney structure
Answer: A — A sac-like outgrowth at the junction of small and large intestine that may assist in digestion/fermentation.
Explanations:
A: Correct — caecum (or caeca) are blind sacs at ileocaecal junction; some role in digestion.
B: Incorrect — caecum is digestive.
C: Incorrect — stomach is muscular sac; not caecum.
D: Incorrect — not kidney. -
The function of maxillary and vomerine teeth in frogs is to:
A. Mastication to chew food into small pieces
B. Hold and prevent escape of prey before swallowing whole
C. Grind plant matter for herbivores only
D. Produce sound during croaking
Answer: B — Hold and prevent escape of prey before swallowing whole.
Explanations:
A: Incorrect — frogs swallow whole; no chewing.
B: Correct — teeth grip prey to stop escape, assisting swallowing.
C: Incorrect — not for grinding plant matter.
D: Incorrect — teeth unrelated to sound. -
The glottis in frog opens into:
A. Oesophagus
B. Trachea leading to lungs
C. Cloaca
D. Buccal cavity only with no respiratory role
Answer: B — Trachea leading to lungs.
Explanations:
A: Incorrect — glottis leads to respiratory tract, not oesophagus (though they lie near each other).
B: Correct — glottis is opening of larynx/trachea to lungs.
C: Incorrect — cloaca unrelated.
D: Incorrect — glottis is key for respiration. -
Swallowing in frog is assisted by:
A. Tongue only; eyes are not involved
B. Eye retraction (bulging eyes) that pushes food into oesophagus and tongue action
C. Hindlimbs forcing food down the throat
D. Vocal sacs pushing food into stomach
Answer: B — Eye retraction (bulging eyes) that pushes food into oesophagus and tongue action.
Explanations:
A: Incorrect — eyes also aid swallowing.
B: Correct — contraction of levator bulbi and eye retraction aids in pushing food posteriorly.
C: Incorrect — hindlimbs not used.
D: Incorrect — vocal sac unrelated. -
Which enzyme is primarily responsible for starch digestion in frog’s digestive system?
A. Pepsin in stomach
B. Pancreatic amylase and possibly salivary-like amylase in gut
C. Lipase in stomach
D. Trypsin in mouth
Answer: B — Pancreatic amylase and possibly salivary-like amylase in gut.
Explanations:
A: Incorrect — pepsin digests proteins.
B: Correct — carbohydrate digestion mainly by amylase from pancreas/intestinal sources.
C: Incorrect — lipase acts on fats.
D: Incorrect — trypsin is protease secreted by pancreas into intestine, not mouth. -
The region where digestive and respiratory tracts bifurcate in frog is the:
A. Buccal cavity/pharynx area with glottis and oesophagus openings
B. Cloaca
C. Heart
D. Tympanum
Answer: A — Buccal cavity/pharynx area with glottis and oesophagus openings.
Explanations:
A: Correct — in the pharyngeal area, openings to respiratory (glottis) and digestive (oesophagus) tracts are present.
B: Incorrect — cloaca is further posterior.
C: Incorrect — heart unrelated.
D: Incorrect — tympanum unrelated. -
Bile acts in digestion primarily by:
A. Chemically digesting proteins
B. Emulsifying fats to increase surface area for lipase action
C. Hydrolyzing nucleic acids
D. Converting starch to sugar
Answer: B — Emulsifying fats to increase surface area for lipase action.
Explanations:
A: Incorrect — bile is not protease.
B: Correct — bile salts emulsify lipids enabling enzymatic digestion.
C: Incorrect — nucleases break nucleic acids; bile does not hydrolyze them.
D: Incorrect — starch digestion by amylase. -
The sphincter controlling flow from small intestine to large intestine in frog is similar to:
A. Cardiac sphincter between oesophagus and stomach
B. Ileocaecal valve/sphincter at ileum to caecum/colon junction
C. Urethral sphincter controlling urine outflow
D. Glottis controlling respiration
Answer: B — Ileocaecal valve/sphincter at ileum to caecum/colon junction.
Explanations:
A: Incorrect — cardiac sphincter is stomach-oesophagus junction; different location.
B: Correct — ileocaecal valve regulates passage into large intestine/caecum.
C: Incorrect — unrelated.
D: Incorrect — glottis is respiratory. -
The primary storage and digestion chamber in frogs is the:
A. Crop
B. Stomach
C. Rectum
D. Gall bladder
Answer: B — Stomach.
Explanations:
A: Incorrect — crop is present in birds, not frogs.
B: Correct — stomach stores and starts protein digestion.
C: Incorrect — rectum stores feces.
D: Incorrect — gall bladder stores bile. -
The mucus secreted in frog’s mouth helps to:
A. Grind food mechanically
B. Lubricate food for swallowing and trapping prey on tongue
C. Produce bile
D. Respiratory gas exchange
Answer: B — Lubricate food for swallowing and trapping prey on tongue.
Explanations:
A: Incorrect — grinding requires teeth/gizzard in birds.
B: Correct — mucous aids prey capture (sticky tongue) and passage of food.
C: Incorrect — bile from liver.
D: Incorrect — mucus not main gas exchange medium. -
During amphibian metamorphosis, the digestive system changes from tadpole to adult: which is true?
A. Tadpoles have a longer intestine adapted to herbivory; adults have shorter intestine for carnivory
B. Tadpoles have lungs like adults from birth
C. Adults develop gills while tadpoles have lungs
D. No significant change in digestive tract occurs
Answer: A — Tadpoles have a longer intestine adapted to herbivory; adults have shorter intestine for carnivory.
Explanations:
A: Correct — tadpoles often herbivorous need longer gut for plant digestion; adults carnivorous have shorter guts.
B: Incorrect — tadpoles have gills initially; lungs develop later.
C: Incorrect — opposite is true.
D: Incorrect — metamorphosis includes significant changes. -
Absorption of digested nutrients in frog occurs mainly in the:
A. Stomach walls only
B. Small intestine (duodenum & ileum) with villi and microvilli increasing surface area
C. Buccal cavity
D. Cloaca lumen only
Answer: B — Small intestine (duodenum & ileum).
Explanations:
A: Incorrect — stomach absorbs few substances.
B: Correct — small intestine enriched with mucosal folds/villi for absorption.
C: Incorrect — buccal cavity limited absorption.
D: Incorrect — cloaca not main absorptive site. -
Which statement best describes the role of the liver and pancreas in frog digestion?
A. Liver produces digestive enzymes; pancreas stores bile
B. Liver produces bile for emulsification of fats; pancreas secretes enzymes (amylase, lipase, proteases) into intestine
C. Both organs are vestigial in frogs
D. Liver and pancreas both store food for hibernation
Answer: B — Liver produces bile for emulsification of fats; pancreas secretes enzymes (amylase, lipase, proteases) into intestine.
Explanations:
A: Incorrect — roles reversed.
B: Correct — standard vertebrate digestive physiology.
C: Incorrect — both organs active.
D: Incorrect — not their main function. -
The main difference between the oesophagus and trachea in frogs is:
A. Oesophagus carries air; trachea carries food
B. Oesophagus is muscular tube for food; trachea is cartilage-supported tube for air
C. Both are identical tubular passages with same function
D. Oesophagus secretes bile into stomach
Answer: B — Oesophagus is muscular tube for food; trachea is cartilage-supported tube for air.
Explanations:
A: Incorrect — reversed.
B: Correct — oesophagus transports food; trachea conducts air to lungs and has supportive rings.
C: Incorrect — different functions and structure.
D: Incorrect — oesophagus doesn’t secrete bile.